When I get new neighbors in my apartment complex, my "wireless" light will blink amber letting me know that someone is scanning for an unsecure wifi signal that they can use for free. It blinks for about 30 seconds and then goes blank- that tells me that they were unsuccessful.

If you see it blink amber and THEN it blinks green- that means they tried to access your signal and are now transmitting data!

NOTE* I have Belkin router firewall on, wireless security on, Panda antivirus, Threatfire antivirus,Windows Defender and have not had a virus, malware, trojan or any other successful attack in over a year!